Ugur Bilgili

Production of sweet sorghum (Sorghum bicolor L. Moench) increases with increased plant densities and nitrogen fertilizer levels

Abstract The main aim of this study was to evaluate the effects of different intra-row spacings and nitrogen levels on forage, dry matter, seed yield and some other yield components of sweet sorghum (Sorghum bicolor L. Moench). Five intra-row spacings (5, 10, 15, 20 and 25u2009cm) and five N fertilization rates (0, 50, 100, 150 and 200u2009kg ha−1) were tested under irrigated conditions in Bursa, Turkey in 2002 and 2003 growing seasons. Yields decreased with increasing intra-row spacing, and increased up to 100 kg N ha−1. Five- or 10u2009cm intra-row spacings and 100 kg N ha−1 fertilization gave more than 80 tonnes (t) ha−1 forage or 30u2009t ha−1 dry matter yield based on pooled data of both years. The two-year average seed yield ranged from 3.15 to 4.53u2009t ha−1, with the highest yield being obtained from the combination of 10–20u2009cm intra-row spacing and 150u2009kg N ha−1. Five- or 10-cm intra-row spacings, and 100 or 150u2009kg ha−1 N fertilization regimes are suggested to maximize forage, dry matter and seed yield in sweet sorghum under similar soil and climatic conditions.

Year-round nitrogen fertilization effects on growth and quality of sports Turf mixtures

Abstract The effect of three different nitrogen (N) levels applied monthly year-round on the growth and quality aspects of four different sports turf mixtures consisting of perennial ryegrass (Lolium perenne L.), tall fescue (Festuca arundinacea Schreb.), Kentucky bluegrass (Poa pratensis L.), creeping red fescue (Festuca rubra var. rubra L.), Chewings fescue (Festuca rubra var. commutata Gaud.), slender red fescue (Festuca rubra var. trichophlla), and Colonial bentgrass (Agrostis tenuis L.) were evaluated in this three year field irrigated study. Nitrogen was applied monthly at rates of low (2.5 g N m− 2), medium (5.0 g N m− 2), and high (7.5 g N m− 2) starting in the first month after the sowing date in November 1998 and continuing for 34 months. The seasonal average differences in color, quality, cover percentages, and clipping yields of the mixtures were not significant. In contrast, N treatments greatly affected these characteristics, and differences were statistically significant at all the individual sampling dates and for seasonal averages during the three years of this study. Turf color and quality were generally associated with the N fertility treatments. Increasing N significantly (P < 0.01) enhanced the color and quality ratings and increased clipping yields in all turf mixtures. Fall and winter fertilizations significantly (P < 0.01) improved color and quality of turf without winter damage in the experimental area with mild winters. In particular, the high (7.5 g N m− 2) rate resulted in decreased rooting at the both 0–15 cm and 15–30 cm depths.

Pathogenicity, reproduction and foraging behaviours of some entomopathogenic nematodes on a new turf pest, Dorcadion pseudopreissi (Coleoptera: Cerambycidae)

Abstract Entomopathogenic nematodes (EPNs) in the families Heterorhabditidae and Steinernematidae have considerable potential as biological control agents of soil-inhabiting insect pests. In the present study, the control potential of the EPNs Steinernema carpocapsae (TUR-S4), S. feltiae (Nemaplus), S. carpocapsae (Nemastar), S. feltiae (TUR-S3) and Heterorhabditis bacteriophora (Nematop) against a new longicorn pest, Dorcadion pseudopreissi Breuning, 1962 (Coleoptera: Cerambycidae), on turf was examined in laboratory studies. Pathogenicity tests were performed at the following doses: 50, 100 and 150 Dauer Juveniles (DJs)/larva at 25°C. Highest mortalities (75–92%) of the larvae were detected at the dose of 150 DJs/larva for all nematodes used. Reproduction capabilities of the used EPNs were examined at doses of 50, 75, 100 and 150 DJs/larva at 25°C. S. carpocapsae (TUR-S4) had the most invasions (32 DJs/larva) and reproduction (28042 DJs/larva) at the dose of 100 DJs, and the highest reproduction (per invaded DJ into a larva) was observed in H. bacteriophora (Nematop) (2402.85 DJs) at a dose of 50 DJs. The foraging behaviour of the nematodes in the presence of D. pseudopreissi and Galleria mellonella L. (Lepidoptera: Galleriidae) larvae was studied using a Petri dish filled with sand at 20°C. All of the used nematodes accumulated near the larvae section of both insect species (32–53% of recovered DJs) with a higher percentage of S. carpocapsae (TUR-S4) (53%) and H. bacteriophora (48%) (Nematop) moving towards larvae of D. pseudopreissi, than the S. feltiae strains.

Control of a new turf pest, Dorcadion pseudopreissi (Coleoptera: Cerambycidae), with the entomopathogenic nematode Heterorhabditis bacteriophora

The use of biological control in turf has increased to avoid possible negative effects on humans. Entomopathogenic nematodes (EPNs) belonging to the families Steinernematidae and Heterorhabditidae have control potential against many economically important insect pests. In the present study, the efficacy of Heterorhabditis bacteriophora against a new pest on turf, Dorcadion pseudopreissi, was examined in the field. Cages (1xa0×xa01xa0×xa01xa0m) with female and male D. pseudopreissi were placed on two kinds of turf: Lolium perenne and Festuca arundinacea. After beetles had deposited eggs into the moist soil surface, the cages were removed and H. bacteriophora was applied at 0.5 million infective juveniles/m2 to half the plots. Application of H. bacteriophora caused a statistically significant reduction in numbers of beetle larvae in L. perenne plots and a non-significant reduction in F. arundinacea plots. The area damaged by D. pseudopreissi was significantly reduced by nematode application in both turf species. The number of nematodes declined after application, but small numbers could still be detected after 6xa0months.

Effect of nitrogen fertilization on quality characteristics of four turf mixtures under different wear treatments

ABSTRACT The effect of three nitrogen (N) application regimes on the color, turf quality, cover, and clipping weights of four different sports type mixtures were evaluated under different wear frequencies for three years in an irrigated field. Nitrogen was applied monthly at rates of low (2.5 g N m− 2), medium (5.0 g N m− 2), and high (7.5 g N m− 2). The turf mixtures were subjected to four different wear treatments at frequencies of zero (control), once per week, once biweekly, and once per month for approximately eight months each experimental year. Wear treatments reduced turf color and quality, cover percentage, and clipping yield. Application of wear every week was detrimental to turf characteristics, whereas wear once every month generally had no significant effect. Nitrogen fertilization resulted in improved color and quality, and increased cover percentage and clipping yield.

Effect of plant growth-promoting Bacillus sp. on color and clipping yield of three turfgrass species

ABSTRACT A two-year irrigated field study was conducted to determine the effects of plant growth-promoting rhizobacteria (PGPR; Bacillus subtilis OSU-142 and Bacillus megaterium M3) as biofertilizer, and in combination with a chemical nitrogen (N) fertilizer, on turf color and clipping yield, and interaction of biofertilizer and chemical N fertilizers in perennial ryegrass (Lolium perenne L.), tall fescue (Festuca arundinacea L. Schreb.), and Kentucky bluegrass (Poa pratensis L.). The three turf species were tested separately in split-plot design experiments with three replications. Three fertilizer sources (ammonium nitrate only, ammonium nitrate + B. megaterium M3, and ammonium nitrate + B. subtilis OSU-142) were the main plots. N applications with monthly applications of 0.0, 2.5, 5.0, and 7.5 g N/m2 were the subplots. Color ratings and clipping yields increased with increasing chemical N fertilizers in all species. Both Bacillus sp. significantly increased color ratings and clipping yields in perennial ryegrass and tall fescue. However, there were no significant differences among the three fertilizer sources in color and clipping yield of Kentucky bluegrass. The experiments showed that there is a small but significant benefit from applying biofertilizers for turf color, and that N fertilization may be reduced in some turf species when biofertilization are made for this purpose.